The Machine Thread

Of almost all the concepts Isaac mentions I found the Self-replicating Machine episode the most tantalising. Can we actually make one?

And it got me thinking, how do you create Mega-Structures, space colonies, mass-produced mirrors or spacescrapers? You need to create a machine to build it for you, but not just any machine: a machine that makes the machine to make it for you.

Or a machine that makes the machine that then makes another in order to make a machine to make it for you. (You get the picture)

So this thread I thought we could jot down ideas on the challenges involved, and any solutions you can think of. For instance I would imagine the following problems, just starting with the basics using today's technology:
- how do you make a machine that makes another one? A 3D printer is the only solution I can think of at the moment. It is conceivable to print one using another.
- however complexity in current 3D printers is rudimentary. They use single pre-made materials and are assembled by hand. We need one that can be printed simply.
- and printing electronics is really hard, so your machine cannot 'think' unless it's possible. In order to print electronics you need materials that need mining and refinement processes that are hard to create and difficult to assemble. So perhaps you have a 'brain' like a central computer, that is manufactured using current-day methods, that 'transmits' instructions simply to 3D printed modules. These modules don't need to think then, they just move and perform tasks.
- they need power. However this could be centralised as well similar to electronics.
- The modules can assemble more modules using an easily workable material - what material I am not sure of, but it needs to be commonly found, easily configurable using only basic gathering and simple bonding techniques. Any material needed can be gathered by gathering modules, heated by heating modules, crushed by crushing modules, all of which must be able to made by the original material.

Which then presents the first question and wall to the concept - what material can be used for the above purpose? Does anyone have any ideas? Also feel free to post other challenges/solutions you could think of too.

Nature has shown us a way. A bacteria is a living machine that divides. Design a machine that grows to a certain point and then splits into two.

The issue of materials
It might be a good idea to have some sort of hierarchy based on the autonomy of our "replicators". Indeed the "what material can be used for the above purposes" makes it sound like we are limited by a rule saying we can only use the materials we have directly on site. It is obviously necessary at some point but definitely not for the grand majority of projects. Remember the early days of the channel when IA gave the example of a way for us to be using all that surplus energy from the growing Dyson swarm. Arguing that we can use it to run industrial sized particle accelerator (e.g. LBNL’s Bevalac) to transmute hydrogen stolen from solar wind or the "surface" of the Sun into the elements we want. And as a bonus we could harness a little bit of the energy produced (up until lead) to lessen the overall power requirement.
Once we have that working it would be inefficient to limit ourselves to only use the elements accessible on site.
Simplifying the work of our machines
The requirements would be to create solar panels (collecting a small portion of the energy) or simple mirrors to use the full extent of solar thermal energy (e.g. Heliostat 1 2 3 4). The energy can be delivered "ready to use" (see power satellite episode from SFIA) or "raw" where the heliostat would be on the construction site, or even just using that raw power to melt/weld/cook stuff. Of course, the two options are not mutually exclusive: a diffraction grating can be used to precisely separate the wavelengths that we can use to run different kind of highly efficient solar cells (each of them having a narrow range of wavelength at high efficiency is interesting) from the rest of it that we could use to simply heat stuff (solar furnace) or even separate the infrared from the few ultraviolet and x-ray and use the latter to catalyze some useful chemical reaction (or even help printing your circuits :)
Doing that first part would be extremely difficult since it is the first thing we construct from only moon "dust" (or mercury's most likely), but once those material and energy issues are out of the way we can become insanely efficient, creating "replicator" that only replicate and build more stuff without the need to worry about how to obtain some weird elements by mining and refining for hours.
Merging different options to enhance our efficiency
I personally think that the solution lies in copying what we already do today: we ultra-specialize. As Migala pointed out with the bio-mecha parallel, having a robot that does absolutely everything by itself in a specific region of space is akin to how human tribes used to work, or how a bacteria reproduce and does stuff... extremely inefficient when compared to our world right now where soon only one country, in one obscure city will be making the absolute best thing in the world and ship it everywhere all around the planet, and that for basically every single product. (only high tech ones obviously not for everyday food)
I am not entirely convinced the machine-replicator thing is necessarily the most efficient way of doing things, something halfway in between that and what we already do today could be enough. And also we should be getting there progressively instead of trying to directly create a machine replicator thingy e.g. building an autonomous factory of car/bicycle then when feel confident enough to build a Mega-factory that creates other car factories. Then a Mega-factory that creates mining factories which would collect and send the materials to the car factory, relieving us of the burden of supervising mining operation etc.
I could totally see bio-engineered microorganisms that would lay "eggs"/baby cells to give birth to an enormous amount of specialized cells that simply eat the food that is in front of them and replicate once then dies leaving its exoskeleton/super-hard body behind. Its poopy "waste" could be made out of a copper oxide that another bacteria would then eat and use high energy radiation to process and leave a trail of copper alloy conducting some current (or any other process that would allow us to have a resilient structures that still have some sort of circulatory system (in the broad sense) to power some specific part or help repair should damage occur)
To guide them we could use a laser to heat up a surface so that bacterias or something would follow the heat and get clustered near it then die. Leaving a trail of "food" which could have very complex patterns (see the circuits link from before). Yes this is dark but so is our "cherished" Mother Nature: thing1 exists then gets eaten alive by thing2 which itself gets gruesomely murdered and eaten by thing3 which then gets cancer etc. ad infinitum. wonderful world right? This trail would then be followed by our specialized hard-shell cells and its numerous successors.
To some extent, this really is already happening with our own species, as our own teeth (the hard part that is super useful) is actually made my ultra specialized cells that build up your teeth and then all die en masse, leaving us humans with a very efficient tool for crushing/cutting food without having to keep on sustaining the cells that created them.
Now "nature" is extremely limited, moving from small chemical potential to another, ever so slightly higher (or lower) at each step. It does the job eventually but takes too much time. What i meant by bio-engineering is something that would be billions of years away from bacterias of today. We need those to be able to use powerful energy sources, jump high energy barrier without being too unstable, and allow them to use compounds/alloys/eutectic mixes that nature itself would never create yet would be far superior and useful for efficient, precise and robust constructions.
I really think that 3D printing and bio-engineering are not mutually exclusive pathways to get to our K2 civilization achievement thingy. However even if all this can most certainly alleviate some problems with heat dissipation, it doesn't eradicate the problem IA talked about in the 3D printing episode about speed/precision/heat dissipation issues. There will still be trade-offs, what matter is to make sure that what we "lose" is something that we don't care about or that is taken care of by another process.
Albeit just using nature as is, would already be a good thing compared to our pathetically unsustainable agriculture practices of today e.g. regardless of ethics issues, i personally wouldn't mind eating a "steak" made out of protein-making-algae is it means a 1000 other people can also eat as much as they need.
I'll edit and add a link the corresponding SFIA episodes I mentioned soon. Nice idea for a long term thread to see all related issues summarized to a single place. Thanks Hub.

Glad you started this! I love self-replicating machine concepts too.

For materials, right now graphene looks the most promising. Depending alone on how you form it, graphene is a:

Rigid mechanical structure
Flexible mechanical structure
Electrical conductor
Semiconductor
Insulator
Light emitter
Solar panel
Transparent panel
Opaque panel
etc.

In short, if we ever master graphene production we can build just about every part of a 3D printer, which will then print - more graphene parts. And being mostly one element means a minimalistic extraction pipeline.

There are also silicon and boron alternatives to graphene, in case carbon is in short supply.

More later I hope...